Facebook allows one Facebook pixel per ad account.  

To create a Facebook pixel:

Start by clicking here: Facebook Ads Manager

If you have not created a pixel code, you will see this screen: click Create a Pixel

Step 1: Click Copy and Paste the Code

This brings up the install pixel screen. Click next until you see the blue Email Instructions button. Then click it.

You will then see a screen that allows you to email the code to yourself.

Copy your Facebook Tracking Pixel ID

Add your Facebook Pixel Tracking ID to your Folio:

Open the Folio to which you wish to add your code from your Folios list (select edit)

Paste the code in SEO section of the Settings Panel.